The heart's septum separates which sides?

• A. Atria and ventricles
• B. Left and right sides
• C. Right and left atria
• D. Aorta and pulmonary artery

Answer: (B)

The septum’s job is to divide the heart into left and right halves. There are two main walls: the interatrial septum, which separates the right and left atria, and the interventricular septum, which separates the right and left ventricles. This separation keeps oxygen-rich blood on the left from mixing with oxygen-poor blood on the right, which is essential for proper circulation. The other ideas don’t fit as well: a single wall between atria and ventricles isn’t how the heart is organized—those chambers are separated by boundaries and valves, not one continuous septum. The aorta and pulmonary artery are vessels that exit the heart, not chambers that are separated by a septum. So the correct takeaway is that the septum divides the left and right sides of the heart.